I. Field of the Invention
This invention relates generally to braking arrangements for snowmobile-type vehicles and more specifically an improved brake arrangement for a snowmobile vehicle of the type having a mono-body suspension system whereby, during braking, weight is transferred to the steerable skis to thereby improve the maneuverability of the vehicle.
II. Discussion of the Prior Art
In a conventional snowmobile suspension system, the orbital path for the track is defined by a plurality of bogie wheels, at least two of which are journaled to the frame and the others being disposed on floating rails which are suspended from the frame by means of linkage arrangements and dash pots. In this conventional arrangement, the tension in the track changes under varying load conditions because of shifts in the relative spacing between the frame-fixed sprocket wheels and the rail-mounted wheels.
More recently, an alternative suspension system has been devised in which track tension remains constant under varying load conditions. The so-called mono-body suspension involves an endless track which is made to traverse an orbital path between a front drive sprocket wheel assembly and a rear driven idler wheel assembly. Intermediate rails and further idler wheels may be used to provide a desired size to the ground-engaging span of the drive track. The track drive sprocket wheels are fixedly attached to a driven shaft which is journaled for rotation between two parallel arm assemblies, one of the arms being the chain case which surrounds the chain and sprocket wheels coupling the drive jack shaft to the driven shaft. The other arm is merely a support arm which is pivotally secured to the end of the jack shaft opposite to that which has the chain sprocket wheel secured thereto. The jack shaft is, in turn, driven by a V-belt from the variable speed drive and clutch associated with the snowmobile's engine. Further details of this mono-body suspension system are set out in a co-pending U.S. application, Ser. No. 498,831, filed May 27, 1983, for "SLIDE RAIL TRACK DRIVE SYSTEM FOR A SNOWMOBILE", which is assigned to the assignee of the present application and in the Taylor patent, U.S. Pat. No. 4,301,884.
The mono-body suspension heretofore described enables the complete track suspension assembly to be pivotally mounted with respect to the chassis or frame of the snowmobile.
In the past, such as in the aforereferenced Taylor patent, it has been the practice to apply a braking force directly between the frame of the vehicle and a disk or drum secured to the V-belt driven jack shaft. While effective to stop the vehicle, that type of braking arrangement does not improve the handling of the snowmobile vehicle during braking.
In accordance with the principles of the present invention, rather than affixing the stationary portion of the braking system, i.e., the brake bands or calipers, to the frame of the vehicle, it is instead fastened to the exterior surface of the pivoting chain case. Now, when the brakes are applied, the resulting reaction forces acting on the chain case tend to lift the front end of the mono-body suspension system and, in doing so, transfer a portion of the weight of the vehicle from the suspension system to the front steerable skis causing them to dig into the snow. As such, the maneuverability or handling capability of the vehicle is improved during braking operation.
It is accordingly a principal object of the present invention to provide a new and improved braking system for a snowmobile-type vehicle.
A related object of the invention is to provide a new and improved braking system for a snowmobile vehicle having a mono-body type suspension.
A yet further object of the invention is to provide a braking system for a snowmobile in which application of the braking forces causes a transfer of weight from the suspension system to the front skis.
A still further object of the invention is to provide a braking system for a snowmobile having a mono-body type suspension in which the rotating brake element is secured to the vehicle's driven jack shaft while the stationary brake bands or caliper pads are fixedly mounted with respect to the pivoting chain case used in the mono-body construction.
These and other objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when considered in conjunction with the accompanying drawings in which like numerals in the several views refer to corresponding parts.